For a few months when i was over there on a work holiday visa. I played a few games for a couple of sides in Brisbane as well as coaching in their youth setups. One of the senior coaches knew someone at the Roar, they then invited me to coach their young goalkeepers until the end of the season.

Maybe slightly harsh, but what i'm getting at is there is no established firm history between clubs, due to the fact that most clubs didn't exist before the A-League started. There can't be a rivalry like say West Ham and Millwall, or Rangers and Celtic etc.

In regards to your second paragraph; The rivalries in the A-League are growing fast. The league might only be 8 years old but there has been enough matches to carve out some fierce derby's. Sure, not on the level of the Old Firm etc., but for example, the Melbourne Derby has turned into a intense rivalry, on and off the pitch and that will only grow.

Like Melbourne/Adelaide because of the two grand finals (+ other games) has been made a pretty fiery clash for supporters and players alike, so there is enough history between (some) clubs to create decent rivalries.